Fluid-ejection printing devices, such as ink jet printers, commonly have at least one ink cartridge and a printhead chassis that supports the ink cartridge. The ink cartridge may contain one or more reservoirs that provide ink or some other fluid to a printhead. If the ink cartridge has more than one reservoir, each such reservoir often retains fluid of a different color for multi-color printing. On the other hand, if the ink cartridge has only a single reservoir, typically such reservoir is used to retain black ink for black-and-white printing.
The printhead is formed of a printhead die, which typically is connected directly or indirectly to the chassis. In order to form an image, the printhead die, along with the chassis and the ink cartridge, generally are moved in a lateral direction across a width of a substrate, such as paper, as fluid is ejected from the printhead. After the printhead forms a row-portion of the image along the width of the substrate, the substrate is advanced in a direction perpendicular to the lateral direction along a length of the substrate, so that the printhead can form a subsequent row-portion of the image. This process of advancing the substrate for each row-portion is repeated until a next substrate is needed or the image is completed.
For proper operation of the printhead and ink cartridge assembly, it is necessary to regulate the pressure within the ink cartridge. Pressure changes may occur during shipping or storage due to air pressure changes or temperature changes, for example. Pressure changes may occur during printing due to depletion of ink within the ink cartridge as ink is gradually used up, or due to surges that occur during acceleration and deceleration at the end of a row of printing. If the fluid pressure is too great, ink may be caused to dribble out of fluid-ejecting nozzles of the printhead die, or too much ink may be ejected. If the fluid pressure is too small, the printhead may experience ink starvation, resulting in too little ink being ejected so that white streaks are apparent in the printed image.
One method of providing pressure regulation is to have a porous capillary media within the ink reservoir of the ink cartridge. The capillary media is typically a rectangular shaped piece of foam or felt. Capillary forces tend to keep the ink at a slightly negative pressure, so that ink does not run out of the printhead nozzles, which are typically positioned at a lower height (i.e., closer to the substrate) than the ink reservoir. The ink cartridge contains a fluid discharge port for ink to travel from the ink reservoir to the printhead chassis through a pipe which serves as the fluid reception port on the chassis. In order to facilitate a steady flow of ink as needed during printing, a common configuration is to provide a wick (also known as a scavenger member, or an ink delivery member) at the fluid discharge port. The wick is in contact with the capillary media and has different capillary properties than the capillary media. When the ink cartridge is loaded into the printhead chassis, typically the wick is forced into contact with a filter member at the mouth of the fluid reception port. Once the printhead is primed so that fluid fills the various ink passageways between the capillary media and the nozzles on the printhead die, capillary forces take care of supplying ink as needed for printing.
When an ink reservoir in the ink cartridge runs out of ink, a user is charged with the responsibility of removing the empty ink cartridge from the chassis and replacing it with a full ink cartridge. The task of replacing an ink cartridge must be simple and clean so that ink is not incidentally discharged during such a replacement process. If ink is discharged during such a replacement process, ink could stain the user's hands or clothes, and it also could drip into areas of the printer where it might cause damage.
For example, conventional ink cartridges include a shipping cap that seals the fluid discharge port(s). The shipping cap helps to prevent ink evaporation during long-term storage, as well as ink spillage due to air pressure changes. The ink cartridge is generally also provided with a vent path to help relieve pressure differences during shipping, storage, and printing. However, when these shipping caps are removed by a user when installing the ink cartridge into a printer, a transient reduction in pressure at the fluid discharge port opening is caused. This transient reduction in pressure can force ink out of the fluid discharge port during removal of the cap and can cause staining or damage.
Accordingly, a need in the art exists for a cap removal solution that allows a user to simply and cleanly remove the shipping cap from a new ink cartridge prior to insertion of the ink cartridge into the printhead chassis.